Incinerator



K. F. TRIGGS INCINERATOR Aug. 19, 1958 2 Sheets-Sheet 2 Filed NOV. 7, 1955 Unite mClNnRAToR Application November 7, 1955, Serial No. 545,236

4 Claims. (Cl. 11G-8) This invention relates to down-draft incinerators and is particularly directed to burners for eciently disposing of burnable refuse with a minimum temperature rise in the exhaust liue thereof and with a minimum of smoke and obnoxious odors.

The smoke, vapor, and gases which rise from a tire of solid-fuel are composed of a mixture of water vapor, flying ash, and carbon particles which are liberated and carried away by the air currents as the solid pieces of fuel gradually rise to combustion or llame temperature. Such volatile products of combustion are, according to this invention, trapped and burned before they are admitted to the exhaust flue so that the flue gases are effectively cleaned.

Incinerators are often charged with large masses of relatively damp refuse. Considerable air and heat is required to dry the mass sufficiently to burn. Unfortunately during the drying phases large quantities of smoke is given olf. As the mass dries out, the amount of air required for combustion is decreased and the temperature of the Hue gases rises. In incinerators heretofore, the temperature rise often becomes dangerously high. Hence, there is the undesirable condition of the incinerator charge giving off objectionable quantities of smoke during the beginning of the burning operation and then proceeding to dangerously high temperatures near the end of the burning operation.

An object of this invention is an incinerator Which taes Patent removes smoke and volatile products of combustion from l the exhaust gases.

Another object of this invention is an incinerator which will not smoke and yet which will produce reasonably low, safe flue temperatures.

The objects of this invention are attained by a combustion chamber within a casing having grates at the bottom and an .air intake opening at the top. The exhaust tiue communicates with the bottom interior of the combustion chamber through a smoke consuming tube, the walls of the tube being heated by a iiuid fuel burner to a temperature well above the burning temperature of smoke given olf from the materials in the combustion chamber. The air intake to the incinerator is selectively divided between two paths, one path being traced in through the top of the combustion chamber, downward through the combustion chamber, laterally along the smoke-consuming tube, and hence upwardly through the flue. The other path by-passes the first path so that air in selective quantities enters the flue directly and hence reduces the quantity of air entering the top of the combustion chamber. The amount of by-passed air is a function of the temperature and velocity of the gases in the Hue.

The above-mentioned and other features and objects of this invention and the manner of attaining them will become more apparent and thet invention itself will be best understood vby reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:

Fig. 1 is a vertical sectional View through the incinerator of this invention; and

Fig. 2 is a vertical sectional view at right angles to the view of Fig. 1.

In the incinerator shown in Figs. 1 and 2 the combustion chamber for receiving the refuse -or other fuel to be burned is comprised of the casing 10. In the particular incinerator shown, the casing is generally tubular in configuration, is upstanding and has walls preferably fabricated from relatively heavy gauge sheet steel. A basket 10a of refractory steel wire may, if desired, be suspended in the casing to hold the charge from the wall of the casing. Enclosing the casing is a light weight jacket 11 supported at the lower end on stand 12 and having a fuel loading door 13 at the top. The fuel loading door, more specifically described in the patent appplication, Serial Number 473,282, tiled December 6, 1954, entitled Incinerator, and .assigned to the assignee of this application, comprises a panel 14 hinged at 14a on the jacket and carrying a bafe plate 15. Thebae plate 15 and panel 14 are spaced apart so that air may move between the two plates and pass downwardly through the opening 16 in the center of the baille plate.

Grates 20 and 21, preferably of the dump or shaker type, are hinged to the front and back walls of the casing 10 near the lower end of the casing. Below the grates is placed the ash receiving pan 22 slidable through an opening in the lower front panel of casing 10. Telescoping flanges on the ash pan and casing opening are employed to make a reasonably tight draft seal at the opening. Ridges 23 may be embossed in the floor of the casing to facilitate insertion and withdrawal of the ash pan.

The exhaust flue 30 extends vertically upward along the inside of the rear wall of the casing 10 and may comprise a sheet metal duct whose rear wall 31b may be Welded to the adjacent sidewall of casing 10. The attachment nipple 31 for joining to the stovepipe or stack is aligned with the liue 30 by means of an appropriately formed plate 31C supported by the casing 10. The jacket 11 is large enough to enclose the casing 10 and to stand away from the walls of the casing to provide a dead air space for heat insulation. The jacket may be enameled or otherwise decorated for pleasing appearance. In the particular embodiment illustrated, the jacket is joined draft-tight by ilange 11a to the bottom end of the casing.

The only air opening to the incinerator, except that which supplies combustion air to an auxiliary burner to be described, is the air intake port 40 in the jacket wall opposite the upper end of Hue 30. Conveniently, air intake port 40 may comprise louvers of measured opening size stamped in the cover plate 41 of the jacket portion 11a. As indicated by arrows in Fig. 1, air flows through the intake port and through openings 31d formed in the plate 31e` to the area above the plate.

According to an important feature of this invention, the draft opening 50 is made in the rear wall of the flue l opposite the `air intake port 40. Conveniently, the draft opening comprises a short nipple, as shown, having a balanced draft Valve 51 pivoted on shaft 52 and eccentrically weighted by adjustable weight 53. The draft opening 50 is aligned with the air intake port so that when damper 51 is opened, varying proportions of the `air entering the air intake port 40 will move directly into the ilue. When the damper is closed, new air entering the air intake port 40 travels through the openings 31d, around the ilue nipple 31, and into the space at the top of the jacket, between the plates 14 and 15 and hence downwardly through opening 16. From opening 16 the new air passes downwardly through the fuel charge in the combustion chamber of the casing.

According to still another important feature of this invention, the only exit for the combustion chamber in casing is through the smoke-consuming tube 60. Tube 60 is of refractory sheet steel, is of a cross sectional size commensurate with the size of flue 30 and communicates at its rear end with the flue. For structural reasons the smoke-consuming tube is preferably welded or otherwise secured at opposite ends to the front and rear walls of casing 10. Further, the tube is, as shown in Fig. 2, centrally disposed in the bottom of the combustion chamber, slightly above the level of the grates 20 and 21. The inlet end of the smoke-consuming tube communicates with the combustion chamber of casing 10 preferably through a semi-circular window 61 cut in the underside of the tube. Ashes and other solid material hence cannot drop into the tube. The outlet end of the smoke-consuming tube communicates substantially draft-tight with the flue 3i). The lower end of the sheet metal duct forming ue 30 is curved at 31a to close olf the flue from the ash pit, so that the ue communicates with the combustion chamber only through the tube 60, to be more fully described below.

The interior of the smoke-consuming tube is heated by an auxiliary source of fuel. The auxiliary heater contemplated here is designed for fluid-type fuel such as the gas burner 62. The nozzle of the burner is aligned with the center of the tube and is supported in the wall of the casing 10. The purpose of the auxiliary source of heat is to raise the walls of the smokeconsuming tube to above a smoke burning temperature. This temperature is preferably at a white or bright red heat. Hence, when the smoke from the combustion chamber of casing 10 enters window 61 and contacts the walls of the tube, the smoke immediately burns. The ying ash and small carbon particles as well as carbon monoxide and various vapors and gases from the combustion chamber are consumed so that the flue discharge is substantially free of odor and visible smoke.

To insure that the smoke passing through the smoke consuming tube contacts the high temperature surfaces, the spiral baffle 63 is disposed in the tube. The spiral bafe in one practical embodiment comprises a sheet of stainless steel twisted, as shown, into a half turn spiral. Such a baffle imparts a spiraling motion to the gases entering window 61, as well as the llame of `burner 62, and moves these gases toward the inner surface of the wall of the tube. The baffle, of course, rises to the temperature of the tube and increases the hot surface area in the tube against which the smoke must travel. To reduce the axial velocity of the flame and to direct the ame toward the tube walls, the `baffle plate 64 also of stainless steel or refractory metal, is reverted to the front end of the spiral bale directly in the path of the liame of nozzle 62.

According to another and important feature of this invention, the interior of the smoke-consuming tube is brought to a temperature well above the smoke-consuming temperature before the charge of fuel in the combustion chamber of casing 16 rises to either smoke or burning temperature. This is effectively accomplished by lining the interior wall of the smoke-consuming tube with a fireclay lining 65. Such clay is preferably of the highly refractory fire-clay variety, has considerable heat inertia and is a good heat insulator. Hence, the application of the ame from burner 62 may quickly raise the interior temperature of the tube to smoke-consuming temperature before the heat of the burner drive smoke and vapor from the solid fuel charge above. Other means of heat insulating the tube may be employed. For example, an expanded steel screen fitted over the top surface of the tube may be attached to the tube to hold the solid fuel out of contact with the tube.

Assume that the combustion chamber of casing 10 is loaded with a mass of damp refuse. When the burner 62 is ignited, the interior of the smoke tube rapidly rises to a high temperature. The heat from the tube slowly raises the temperature of the damp refuse to dry the material and gradually raise that material to ignition temperature. During this time the smoke 'from the fuel charge is drawn downwardly around the tube 60, upwardly through window 61, and rearwardly into contact with the hot spiral `baille and tube walls. At this stage the velocity upward in the ue 30 and the temperature is relatively low and damper 51 remains closed. That is, all of the air taken in at the air intake port 40 passes into the combustion chamber through the opening 16 at the top of the `chamber and downwardly through the damp fuel charge. As the moisture content of the charge reduces and burning increases, the Volume and temperature of the smoke and gases entering tube 60 increases. But, as the flue gas velocity increases, the damper 51 begins to open. This accomplishes two purposes, the Volume of air to the combustion chamber is partially by-passed directly to the flue and the combustion chamber air is reduced. Secondly, the by-passed air is cool and tends to hold down the temperature of the gases in the flue. Hence, the temperature of the ue gases can be held within relatively narrow, safe limits throughout the burning of the damp charge in casing 10.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and considerations and, accordingly, it is desired to comprehend such modifications within this invention as may fall within the `scope of the appended claims.

The invention claimed is:

l. A down-draft incinerator comprising an upstanding tubular casing, a jacket enclosing said casing, a refuse receiving door at the top of the casing, means forming an air intake opening through the top of said casing between the interior of the casing and the interior of said jacket, -a grate across the bottom of said casing, 'a smokeconsuming tube across the bottom of said casing, a fluidfuel burner extending into said tube, an updraft flue, said flue Icommunicating with said smoke-consuming tube, an air intake port in said jacket, a draft opening in said flue, said intake port communicating with said air intake opening to the casing and with said draft opening, and a balanced weight damper in said draft opening to regulate the relative amounts of air which moves into said 4casing and directly into said ilue.

2. I n `combination in a down-draft fuel burner, a tubular casing `forming a combustion chamber, grates at the bottom of the casing and means forming an air inlet opening at the top, a closed Hue, Ian elongated smokeconsuming tube in the grate-end of the casing sealed at one end to said flue and communicating at the other end only with the combustion chamber of said casing to provide a draft passage consisting of said air inlet opening, said casing and said tube, a fluid-fuel burner extending into said tube, and :an air by-pass opening in said flue with a damper responsive to air pressure in the flue.

3. In combination, a burner, a sheet-metal tubular casing upstanding and with grates at the bottom of the casing, means forming an air intake passage at the top of said casing, a flue disposed vertically along one side of said casing and communicating with the space in the lower portion of the casing, said ue having a draft opening :adjacent the upper end of the casing, a balanced damper in the draft opening; a jacket enclosing said casing, flue and draft opening substantially draft-tight, said jacket having an air intake port opposite said draft opening and communicating with said air intake opening and the top of said casing.

4. A burner of the class described comprising a tubular upstanding sheet-metal casing with an air inlet passage at the top of the casing, grates across the bottom end of said casing, `a flue interiorly of `and disposed along one side of lsaid casing, a smoke-consuming tube in the bottom References Cited in the le of this patent UNITED STATES PATENTS lMcKinley Mar. 20, Stout June 9, Greemen July 28, Martin June 21, 

